1. Field of the Invention
This document relates to an organic light emitting diode (OLED) display.
2. Discussion of Related Art
An organic light emitting element used in an organic light emitting diode (OLED) display has a self-emission structure in which a light emitting layer is formed between two electrodes on a substrate.
The OLED display may be classified into a top emission type OLED display, a bottom emission type OLED display, and a dual emission type OLED display depending on an emitting direction of light. The OLED display may be classified into a passive matrix type OLED display and an active matrix type OLED display depending on a driving manner.
A subpixel of the OLED display includes a switching transistor, a drive transistor, a capacitor, an anode electrode, a cathode electrode, and an organic light emitting layer. Because the subpixel having the above-described structure is weak in moisture or oxygen, a multi-layered protective layer having several dozen layers is formed on the subpixel.
In a related art, a multi-layered protective layer on a subpixel is disadvantageous in a mass production aspect. However, the multi-layered protective layer can reduce the generation of a pin hole and can lengthen a traveling path of penetrating moisture to increase penetration time of moisture into a cathode electrode and an organic light emitting layer of the OLED display. In other words, the moisture penetration is delayed. Hence, life span of the related OLED display can increase.
The related art multi-layered protective layer can delay the moisture penetration, but cannot hinder the penetration of moisture. Hence, the multi-layered protective layer is not advantageous in the mass production and the life span.